Hardeners for epoxy resins, processes for producing the same and methods of using the same

ABSTRACT

Hardeners for epoxy resins produced by reacting one or more α,β-unsaturated carboxylic acid esters with one or more aminopolyalkylene oxide compounds, reacting the thus formed intermediate with one or more polyhydroxy compounds, reacting the thus formed intermediate with one or more polyepoxide compounds, and reacting the thus formed intermediate with one or more amines are described. Processes for their production, aqueous dispersions containing the same and methods for their use are also described.

BACKGROUND OF THE INVENTION

Curable epoxy resins have been used for many years as components incoating compositions. However, the properties of coatings produced usingaqueous epoxy resin dispersions have long been considered inferior tothose of coating in which the resin is used in the form of a solution inan organic solvent. This was mainly attributed to the fact that theemulsifiers used, for example nonylphenol ethoxylates, migrate to thesurface of the film where they adversely affect its properties. One wayof solving this problem is to use so-called reactive emulsifiers which,where the epoxy resin is crosslinked with a diamine or polyamide orother hardener, react with the hardener and thus become part of thecoating. Aqueous dispersions of special reactive emulsifiers are knownfrom the prior art.

EP-A-605 and U.S. Pat. No. 4,197,389 describe a hardener in the form ofa reaction product of a) at least one polyepoxy compound, b) at leastone polyalkylene polyether polyol and c) at least one polyamine.

EP-A-387 418, EP-A-714 924 and U.S. Pat. No. 5,489,630 describehardeners for epoxy resins which are obtained by reacting polyalkylenepolyether amines with di- and/or polyepoxy compounds to form anintermediate product and reacting the intermediate product obtained witha primary or secondary amine.

EP-A-717 059 describes hardeners for epoxy resins which are obtained byreacting a polyalkylene oxide polyether monoalcohol with a polyepoxideto form an intermediate product and reacting the intermediate productobtained with a polyamine.

EP-A-717 063 describes hardeners for epoxy resins which are obtained byreacting a polyalkylene oxide monoamine with di- and/or polycarboxylicacids to form an intermediate product and reacting the intermediateproduct obtained with a diamine or polyamine.

EP-A-709 418 describes a hardener for epoxy resins which is obtained byreaction of (A) a polyamine, (B) an alkoxy polyethylene polyethercompound containing epoxy groups and (C) a hydrophobic epoxy compound.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to hardeners for epoxy resins,the hardeners based on α,β-unsaturated carboxylic acid esters, processesfor their production, aqueous dispersions containing such hardeners, andto their use in coating solid substrates.

The problem addressed by the present invention was to provide hardenersfor curable epoxy resins which, unless they were soluble in water, onthe one hand would be self-dispersible in water, but which in additionwould also be suitable as dispersants for curable epoxy resins inaqueous media.

The expression “self-dispersible” in the context of the presentinvention means that the hardeners can be dispersed or emulsifiedspontaneously in aqueous media without the use of additional additives,such as emulsifying or dispersing additives. In other words, thehardeners to be developed are those which would be capable ofself-dispersion and/or self-emulsification in aqueous media. In theinterests of simplicity, the term “self-dispersing” is used for thisproperty throughout the present specification.

The hardeners to be developed would be above all so-called reactivehardeners, i.e. over and above the properties mentioned, namelyself-dispersibility in water and, in addition, suitability asdispersants for curable epoxy resins in aqueous media, would be capableof reacting with curable epoxy resins, i.e. of being hardeners forcurable epoxy resins.

Another problem addressed by the invention was to provide aqueousdispersions of self-dispersible hardeners which would be distinguishedby high stability in storage under practical storage conditions.

Another problem addressed by the invention was to provide coatingcompositions containing a self-dispersible hardener, the coatingobtained from the coating composition after the hardening process beingdistinguished by excellent properties.

It has now surprisingly been found that hardeners obtainable by reactionof α,β-unsaturated carboxylic acid esters with mono-, di- orpolyaminopolyalkylene oxide compound, subsequent reaction of theintermediate product obtained with an aromatic polyhydroxy compound,further reaction with an epoxy resin known from the prior art and,finally, reaction with one or more primary and/or secondary aminesexcellently satisfy the requirements mentioned in every respect.

The present invention relates first to hardeners for curable epoxyresins obtainable by

(a) reacting one or more α,β-unsaturated carboxylic acid esters (I)

R²R³C═C(R⁴)COOR¹  (I)

where R¹ is an aromatic or aliphatic radical containing up to 15 carbonatoms, the substituents R², R³ and R⁴ independently of one anotherrepresent hydrogen, branched or unbranched, aliphatic or aromatic groupscontaining up to 20 carbon atoms or a group —(CH₂)_(n)—COOR¹, where R¹is as defined above and n is a number of 0 to 10, with

(b) one or more mono-, di- or polyaminopolyalkylene oxide compounds,compounds (a) and (b) being used in such quantities that the equivalentratio of the reactive hydrogen atoms at the aminonitrogen atoms of (b)to the C═C double bond in the α,β-position to the group COOR¹ shown informula (I) in the carboxylic acid esters (a) is in the range from 10:1to 1: 10,

subsequently reacting the intermediate product Z1 obtained with

(c) one or more polyhydroxy compounds, the equivalent ratio of estergroups in the intermediate compound Z1 to hydroxy groups in thepolyhydroxy compound (c) being adjusted to a value of 1:1.1 to 1-10,

and subsequently reacting the intermediate product Z2 obtained with

(d) one or more polyepoxides, the equivalent ratio of oxirane rings inpolyepoxide (d) to hydroxyl groups in the intermediate product Z2 beingadjusted to a value of 1.5:1 to 6:1,

and subsequently reacting the intermediate product Z3 obtained with

(e) one or more primary and/or secondary amines, the equivalent ratio ofoxirane rings in the intermediate product Z3 to the reactive H atoms atthe aminonitrogen atoms of (e) being adjusted to a value of 1:1.5 to1:20.

The hardeners according to the invention are either liquid or solidsubstances, depending on their molecular weight.

The present invention also includes processes for the production ofhardeners for curable epoxy resins.

DETAILED DESCRIPTION OF THE INVENTION

The expression “equivalent ratio” is familiar to the expert. The basicconcept behind the notion of the equivalent is that, for every substanceparticipating in a reaction, the reactive groups involved in the desiredreaction are taken into consideration. By indicating an equivalentratio, it is possible to express the ratio which all the variousreactive groups of the compounds (x) and (y) used bear to one another.It is important in this connection to bear in mind that a reactive groupis understood to be the smallest possible reactive group, i.e. thenotion of the reactive group is not identical with the notion of thefunctional group. In the case of H-acid compounds, this means forexample that, although OH groups or NH groups represent such reactivegroups, NH₂ groups with two reactive H atoms positioned at the samenitrogen atom do not. In their case, the two hydrogen atoms within thefunctional group NH₂ are appropriately regarded as reactive groups sothat the functional group NH₂ contains two reactive groups, namely thehydrogen atoms. Example: if a compound (a) containing one olefinicdouble bond in the α,β-position to a carboxyl group per molecule isreacted with a compound (b) containing one NH₂ group per molecule by aMichael addition, compound (a) is regarded as containing one reactivegroup C═C per molecule whereas compound (b) is regarded as containingtwo reactive hydrogen atoms attached to the nitrogen. If, now, (a) and(b) were to be reacted in an equivalent ratio of 1:1, one mole of (a)would have to be reacted with half a mole of (b) because (b) does ofcourse contain two reactive groups per molecule. By contrast, for anequivalent ratio of (a) to (b) of 1:2, 1 mole of (a) would have to bereacted with 1 mole of (b). An equivalent ratio of, for example, (a) to(b) of 1:10 could of course also be adjusted although in that case 1mole of (a) would have to be reacted with 5 moles of (b). This wouldmean that component (b) would be used in excess because, of course, atmost 1 mole of component (b) could theoretically be reacted with (a) ina Michael addition.

In one embodiment, compounds (a) and (b) are used in such quantitiesthat the equivalent ratio of reactive hydrogen atoms at theaminonitrogen atoms of (b) to the C═C double bond in the α,β-position tothe group COOR¹ in formula (I) in the carboxylic acid esters (a) is inthe range from 4:1 to 1:4 and more particularly in the range from 2.5:1to 1.5:1.

In another embodiment, the equivalent ratio of ester groups in theintermediate compound Z1 to hydroxy groups in the polyhydroxy compound(c) is adjusted to a value of 1:1.4 to 1:3.

In another embodiment, the equivalent ratio of oxirane rings in thepolyepoxide (d) to hydroxyl groups in the intermediate product Z2 isadjusted to a value in the range from 2.5:1 to 3.5:1.

Examples of α,β-unsaturated carboxylic acid esters (a) corresponding toformula (I) to be used in accordance with the invention are methylacrylate, ethyl acrylate, dimethyl maleate, diethyl maleate, dimethylfumarate, diethyl fumarate, dimethyl itaconate, diethyl itaconate.Particularly preferred compounds (a) are dialkyl maleates, moreparticularly diethyl maleate and dimethyl maleate.

Suitable amino components (b) are mono-, di- or polyaminopolyalkyleneoxide compounds. By this is meant that these compounds contain on theone hand one, two or more amino functions (NH or NH₂ functions) and, onthe other hand, alkylene oxide units. The alkylene oxide units are, inparticular, ethylene oxide, propylene oxide and butylene oxide, ethyleneoxide and propylene oxide being particularly preferred. The compounds(b) are substances at least partly soluble in water at 20° C.

The production of the compounds (b) is known from the prior art andcomprises the reaction of hydroxyfunctional compounds with alkyleneoxides and subsequent conversion of the resulting terminal hydroxylgroups into amino groups.

So far as the reaction of hydroxyfunctional compounds with alkyleneoxides is concerned, ethoxylation and propoxylation are of particularimportance. The following procedure is usually adopted: in a first step,the required hydroxyfunctional compounds are contacted with ethyleneoxide and/or propylene oxide and the resulting mixture is reacted in thepresence of an alkaline catalyst at temperatures in the range from 20 to200° C. Addition products of ethylene oxide (EO) and/or propylene oxide(PO) are obtained in this way. The addition products are preferably EOadducts or PO adducts or EO/PO adducts with the particularhydroxyfunctional compound. In the case of the EO/PO adducts, theaddition of EO and PO may be carried out statistically or blockwise.

In one embodiment, substances with the general formulaR⁸—O—R⁹—CH₂CH(R¹⁰)—NH₂ are used as the compounds (b). In this formula:

R⁸ is a monofunctional organic group containing 1 to 12 carbon atomswhich may be aliphatic, cycloaliphatic or aromatic,

R⁹ is a polyoxyalkylene group made up of 5 to 200 polyoxyalkylene units,more particularly EO and/or PO units,

R¹⁰ is hydrogen or an aliphatic radical containing up to 4 carbon atoms.

In the context of the present invention, particularly suitablerepresentatives of the compounds (b) are the “Jeffamines” known to theexpert which are commercially available substances. One example is“Jeffamine 2070” which, according to the manufacturer Texaco, isproduced by reacting methanol with ethylene oxide and propylene oxideand then converting the terminal hydroxyl groups of the intermediateproduct initially obtained into amine groups (cf. WO 96/20971, page 10,lines 12-15).

The compounds (b) preferably have average molecular weights (numberaverage Mn) of 148 to 5,000 and more particularly in the range from 400to 2,000.

The polyhydroxy compounds (c) may be aliphatic or aromatic.

In one embodiment, the polyols (c) are selected from the class ofspecial aliphatic diols, namely the alkanediols, polyether diols andpolyesterdiols.

The alkanediols are compounds corresponding to the general formulaHOCH₂—R⁵—CH₂OH, where R⁵ is a hydrophobic hydrocarbon radical which maybe saturated or unsaturated, linear or branched and may also containaromatic structural elements. Examples are hexane-1,6-diol,heptane-1,7-diol and octane-1,8-diol, polyoxytetramethylenediols—alsoknown as polytetrahydrofurans—and the so-called dimerdiols.

Dimerdiols are well-known commercially available compounds which areobtained, for example, by reduction of dimer fatty acid esters. Thedimer fatty acids on which these dimer fatty acid esters are based arecarboxylic acids which may be obtained by oligomerization of unsaturatedcarboxylic acids, generally fatty acids, such as oleic acid, linoleicacid, erucic acid and the like. The oligomerization is normally carriedout at elevated temperature in the presence of a catalyst, for exampleof alumina. The substances obtained—dimer fatty acid of technicalquality—are mixtures in which the dimerization products predominate.However, small amounts of higher oligomers, more particularly the trimerfatty acids, are also present. Dimer fatty acids are commerciallyavailable products and are marketed in various compositions andqualities. Abundant literature is available on the subject of dimerfatty acids, cf. for example the following articles: Fette & Öle 26(1994), pages 47-51; Speciality Chemicals 1984 (May Number), pages17,18,22-24. Dimerdiols are well-known among experts, cf. for example amore recent article in which inter alia the production, structure andchemistry of the dimerdiols are discussed: Fat Sci. Technol. 95 (1993),No. 3, pages 91-94. According to the invention, preferred dimerdiols arethose which have a dimer content of at least 50% and more particularly75% and in which the number of carbon atoms per dimer molecule is mainlyin the range from 36 to 44.

Polyetherdiols in the context of the present invention are diolscorresponding to the general formula HOCH₂—R⁶—CH₂OH, where R⁶ is ahydrophobic hydrocarbon radical which may be saturated or unsaturated,linear or branched and may also contain aromatic structural elements andin which one or more CH₂ units must each be replaced by an oxygen atom.

A particularly attractive class of polyetherdiols can be obtained byalkoxylation of alkanediols, such as ethane-1,2-diol, propane-1,3-diol,propane-1,2-diol, butane-1,4-diol, butane-1,3-diol, pentane-1,5-diol,hexane-1,6-diol, heptane-1,7-diol and octane-1,8-diol,polyoxytetramethylenediols (polytetrahydrofurans) and dimerdiols. Theproduction of these alkoxylated diols is normally carried out asfollows: in a first step, the required diol is contacted with ethyleneoxide and/or propylene oxide and the resulting mixture is reacted in thepresence of an alkaline catalyst at temperatures of 20 to 200° C.Addition products of ethylene oxide (EO) and/or propylene oxide (PO)onto the diol used are obtained in this way. The addition products aretherefore EO adducts or PO adducts or EO/PO adducts with the particulardiol; in the case of the EO/PO adducts, the addition of EO and PO maytake place statistically or blockwise.

Polyesterdiols in the context of the invention are diols correspondingto the general formula HOCH₂—R⁷—CH₂OH, where R⁷ is a hydrophobichydrocarbon radical which may be saturated or unsaturated, linear orbranched and may also contain aromatic structural elements and in whichone or more CH₂ units must each be replaced by a COO unit. They arenormally produced by reacting difunctional polyols with dicarboxylicacids or anhydrides thereof. Commonly used polyols are ethylene glycol,propane-1,2-diol, butane-1,4-diol, hexane-1,6-diol. Typical dicarboxylicacids are succinic acid, adipic acid, phthalic anhydride.Hexane-1,6-diol adipic acid polyesters are particularly preferred.

Examples of suitable aromatic compounds (c) are resorcinol,hydroquinone, 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A), isomermixtures of dihydroxydiphenyl methane (bisphenol F), tetrabromobisphenolA, 4,4′-dihydroxydiphenyl cyclohexane,4,4′-dihydroxy-3,3-dimethyldiphenyl propane, 4,4′-dihydroxydiphenyl,4,4′-dihydroxybenzopenol, bis-(4-hydroxyphenyl)-1,1-ethane,bis-(4-hydroxyphenyl)-1,1-isobutane, bis-(4-hydroxyphenyl)-methane,bis-(4-hydroxyphenyl(-ether, bis-(4-hydroxyphenyl)-sulfone etc. and thechlorination and bromination products of the above-mentioned compounds.Bisphenol A is most particularly preferred as compound (c).

The epoxy compounds (d) are polyepoxides containing on average at leasttwo epoxy groups per molecule. These epoxy compounds may be bothsaturated and unsaturated and aliphatic, cycloaliphatic, aromatic andheterocyclic and may also contain hydroxyl groups. They may also containsubstituents which do not cause any troublesome secondary reactionsunder the mixing and reaction conditions, for example alkyl or arylsubstituents, ether groups and the like. These epoxy compounds arepreferably polyglycidyl ethers based on polyhydric, preferably dihydricalcohols, phenols, hydrogenation products of these phenols and/ornovolaks (reaction products of mono- or polyhydric phenols withaldehydes, more particularly formaldehyde, in the presence of acidiccatalysts). The epoxy equivalent weights of these epoxy compounds arepreferably between 160 and 500 and more preferably between 170 and 250.The epoxy equivalent weight of a substance is the quantity of thesubstance (in grams) which contains 1 mole of oxirane rings. Preferredpolyhydric phenols are the compounds described under (c). Thepolyglycidyl ethers of polyhydric alcohols are also suitable. Examplesof such polyhydric alcohols are ethylene glycol, diethylene glycol,triethylene glycol, 1,2-propylene glycol, polyoxypropylene glycols(n=1-20), 1,3-propylene glycol, 1,4-butylene glycol, pentane-1,5-diol,hexane-1,6idol, hexane-1,2,6-triol, glycerol andbis-(4-hydroxycyclohexyl)2,2-propane.

Other suitable compounds (d) are polyglycidyl ethers of polycarboxylicacids obtained by reaction of epichlorohydrin or similar epoxy compoundswith an aliphatic, cycloaliphatic or aromatic polycarboxylic acid, suchas oxalic acid, succinic acid, adipic acid, glutaric acid, phthalicacid, terephthalic acid, hexahydrophthalic acid,2,6-naphthelenedicarboxylic acid and dimerized linolenic acid. Examplesare adipic acid diglycidyl ester, phthalic acid diglycidyl ester andhexahydrophthalic acid diglycidyl ester. A comprehensive list ofsuitable epoxy compounds (d) can be found in:

A. M. Paquin, “Epoxidverbindungen und Epoxidharze”, Springer-Verlag,Berlin 1958, Chapter V, pages 308 to 461 and

Lee, Neville “Handbook of Epoxy Resins” 1967, Chapter 2, pages 201 and2-33.

Mixtures of several epoxy compounds (d) may also be used,

Amines (e) suitable for the purposes of the invention are primary and/orsecondary amines. Preferred amines (e) are polyamines containing atleast two nitrogen atoms and at least two active aminohydrogen atoms permolecule. Aliphatic, aromatic, aliphatic-aromatic, cycloaliphatic andheterocyclic di- and polyamines may be used.

The following are examples of suitable amines (e): polyethylene amines(ethylene diamine, diethylene triamine, triethylene tetramine,tetraethylene pentamine, etc.), 1,2-propylene diamine, 1,3-propylenediamine, 1,4-butane diamine, 1,5-pentane diamine, 1,3-pentane diamine,1,6-hexane diamine, 3,3,5-trimethyl-1,6-hexanediamine,3,5,5-trimethyl-1,6-hexane diamine, 2-methyl-1,5-pentane diamine,bis-(3-aminopropyl)-amine, N,N′-bis-(3-aminopropyl)-1,2-ethane diamine,N-(3-aminopropyl)-1,2-ethane diamine, 1,2-diaminocyclohexane,1,3-diaminocyclohexane, 1,4-diaminocyclohexane, aminoethyl piperazines,the poly(alkylene oxide)diamines and triamines (such as, for example,Jeffamine D-230, Jeffamine D400, Jeffamine D-2000, Jeffamine D-4000,Jeffamine T-403, Jeffamine EDR-148, Jeffamine EDR-192, Jeffamine C-346,Jeffamine ED-600, Jeffamine ED-900, Jeffamine ED-2001), meta-xylyenediamine, phenylene diamine, 4,4′-diaminodiphenyl methane, toluenediamine, isophorone diamine, 3,3′-dimethyl4,4′-diaminodicyclohexylmethane, 4,4′-diamnodicyclohexylmethane, 2,4′-diaminodicyclohexylmethane, the mixture of poly(cyclohexylaromatic)amines attached by amethylene bridge (also known as MBPCM) and polyaminoamides.

Other suitable compounds (e) are the reaction products of the aminesjust mentioned with the above-described α,β-unsaturated carboxylic acidesters (a) and the reaction products of the amines just mentioned withthe above-described polyepoxy compounds (d).

The present invention also relates to a process for the production ofhardeners for curable epoxy resins comprising the steps of

(a) reacting one or more α,β-unsaturated carboxylic acid esters (I)

R²R³C═CC(R⁴)COOR¹  (I)

where R¹ is an aromatic or aliphatic radical containing up to 15 carbonatoms, the substituents R², R³ and R⁴ independently of one anotherrepresent hydrogen, branched or unbranched, aliphatic or aromatic groupscontaining up to 20 carbon atoms or a group —(CH₂)_(n)—COOR¹, where R¹is as defined above and n is a number of 0 to 10, with

(b) one or more mono-, di- or polyaminopolyalkylene oxide compounds,compounds (a) and (b) being used in such quantities that the equivalentratio of the reactive hydrogen atoms at the aminonitrogen atoms of (b)to the C═C double bond in the α,β-position to the group COOR¹ shown informula (I) in the carboxylic acid esters (a) is in the range from 10:1to 1:10,

subsequently reacting the intermediate product Z1 obtained with

(c) one or more polyhydroxy compounds, the equivalent ratio of estergroups in the intermediate compound Z1 to hydroxy groups in thepolyhydroxy compound (c) being adjusted to a value of 1:1.1 to 1-10,

and subsequently reacting the intermediate product Z2 obtained with

(d) one or more polyepoxides, the equivalent ratio of oxirane rings inpolyepoxide (d) to hydroxyl groups in the intermediate product Z2 beingadjusted to a value of 1.5:1 to 6:1,

and subsequently reacting the intermediate product Z3 obtained with

(e) one or more primary and/or secondary amines, the equivalent ratio ofoxirane rings in the intermediate product Z3 to the reactive H atoms atthe aminonitrogen atoms of (e) being adjusted to a value of 1:1.5to1:20.

The present invention also relates to aqueous dispersions containinghardeners according to the invention. The content of the hardenersaccording to the invention in these dispersions is between 40 and 70% byweight, based on the dispersion as a whole.

The production of aqueous dispersions of the hardeners according to theinvention is generally carried out as follows: the water is added to thehardeners with vigorous stirring at around 60° C. With readilywater-soluble hardeners, an aqueous solution is initially formed; withpoorly water-soluble hardeners, a w/o dispersion is initially formed,ultimately changing into an o/w dispersion as more water is added.

In many cases, aqueous dispersions containing the hardeners obtainableby the process according to the invention are distinguished by verysmall mean particle sizes of around 500 nm or smaller. This leads tovery favorable material properties of the coatings formed with thesedispersions. Particularly favorable material properties are obtainedwhen the mean particle size is below about 300 nm. The mean particlesize is defined as the average of the particle sizes which is obtainedby adding the values of n individual measurements and then dividing thetotal by n. For the purposes of the present invention, the mean particlesizes were determined using a “Coulter N4 Plus Submicron Particle Sizer”(manufacturer: Coulter, Miami, Fla. 33196, USA). This instrument usesthe scattering of laser light at a heavily diluted dispersion forparticle size determination. It performs a number of individualmeasurements and gives the mean particle size as the end result. Theabove-mentioned values relate to scattering measurements at an angle of90° relative to the incident laser beam.

The reactive hardeners according to the invention are suitable incombination with suitable epoxy resins and additives for the productionof coatings, intermediate coatings, paints, molding compositions andcurable pastes for various applications. For example, they may be usedfor the production of protective and/or decorative coatings on various,above all rough and porous substrates such as, for example, wood,mineral substrates (for example concrete and stone), glass, plastics(for example polyethylene, polypropylene), compost materials, ceramicsand pretreated or non-pretreated metals. Their favorable properties alsomake the hardeners according to the invention eminently suitable forone-coat lacquering/painting. The adhering coating layer may remainunchanged as such although it may also serve as an intermediate layer,i.e. as a substrate for further coatings which in turn may consist ofthe same coating material or of another typical coating material. Byvirtue of their good dilutability and their favorable properties, thehardeners according to the invention or rather the dispersions preparedfrom them are also suitable for additional use in electrodepositionpainting. The hardeners according to the invention may also be used forthe production of water-dilutable adhesives. They may also be used asbinders for textile, organic and/or inorganic materials and as anadditive in plastic cements.

Accordingly, the present invention also relates to the use of thehardeners according to the invention for systems (compositions) forcoating solid substrates.

Where the hardeners according to the invention are used for curing epoxyresins, other suitable hardeners (for example polymercaptans,polyisocyanates, imidazoles, polyamidoamines and any of the amines (e))and the additives typically used in the coating industry may also beused.

EXAMPLES

The expression “epoxy equivalent weight” familiar to the expert is usedin the following. The epoxy equivalent weight of a substance is definedas the quantity of that substance (in grams) which contains 1 mole ofoxirane rings.

In Examples 3 and 4, a “Coulter N4 Plus Submicron Particle Sizer”(manufacturer: Coulter, Miami, Fla. 33196, USA) was used to determinethe mean particle sizes. The measured values relate to scatteringmeasurements at an angle of 90° relative to the incident laser beam.

I. Intermediate Products Example 1

17.5 g of diethyl maleate were added dropwise with stirring at 80° C. to200.0 g of monoaminopolyethylene oxide (“Jeffamine M 2070”, Huntsman),followed by stirring for another 60 minutes at 80° C. 91.3 g ofbisphenol A and 0.5 g of triphenylphosphine were then added, the mixturewas heated for 2 h to 200° C. and, after the addition of 456.0 g ofChemres E20 (bisphenol A-based epoxy resin of Henkel SpA, average epoxyequivalent weight ca. 190 g), was heated for another 2 at 200° C. Oncompletion of the reaction, the reaction mixture was diluted with 100 mlof ethoxypropanol.

Example 2

17.5 g of diethyl maleate were added dropwise with stirring at 80° C. to100.0 g of diaminopolyethylene oxide (“Jeffamine ED 2001”, Huntsman),followed by stirring for another 60 minutes at 80° C. 91.3 g ofbisphenol A and 0.5 g of triphenylphosphine were then added, the mixturewas heated for 2 h to 200° C. and, after the addition of 456.0 g ofChemres E20 (bisphenol A-based epoxy resin of Henkel SpA, average epoxyequivalent weight ca. 190 g), was heated for another 2 at 200° C. Oncompletion of the reaction, the reaction mixture was diluted with 100 mlof ethoxypropanol.

II. Hardeners According to the Invention Example 3

226.2 g of the intermediate product obtained as described in Example 1were added dropwise at 100° C. to 85.2 g of IPDA(5-amino-1,3,3-trimethyl cyclohexane methane amine=isophorone diamine),followed by stirring for 1 hour at 80° C.

Example 4

200.0 g of the intermediate product obtained as described in Example 2were added dropwise at 80° C. to 132.6 g of MXDA(3-(aminomethyl)benzylamine), followed by stirring for 1 hour at 80° C.The free amine was then distilled off in vacuo.

III. Aqueous Dispersions of the Hardeners Example 5

200 g of water were slowly added dropwise with vigorous stirring at 60°C. to 200 g of the hardener produced as described in Example 3. Theresulting dispersion had a mean particle size of ca. 130 nm.

Example 6

200 g of water were slowly added dropwise with vigorous stirring at 60°C. to 200 g of the intermediate product obtained as described in Example4. The resulting dispersion had a mean particle size of ca. 430 nm.

What is claimed is:
 1. A process for producing hardeners for epoxyresins, the process comprising: (i) reacting (a) one or moreα,β-unsaturated carboxylic acid esters of the general formula (I),R²R³C═C(R⁴)COOR¹  (I),  with (b) one or more aminopolyalkylene oxidecompounds having at least one aminonitrogen atom with one or morereactive hydrogen atoms, wherein R¹ represents a hydrocarbon radicalhaving up to 15 carbon atoms, wherein R², R³, and R⁴ each independentlyrepresents a substituent selected from the group consisting of hydrogen,hydrocarbon radicals having up to 20 carbon atoms, and —(CH₂)_(n)—COOR¹,wherein R¹ is as defined above and n represents a number of from 0 to10, and wherein (a) and (b) are present in quantities such that theequivalent ratio of the reactive hydrogen atoms in (b) to the α,β C═Cdouble bonds in (a) is from 10:1 to 1:10, to form an intermediateproduct Z1 having a number of ester groups; (ii) reacting theintermediate product Z1 with (c) one or more polyhydroxy compoundshaving a number of hydroxy groups, wherein the intermediate product Z1and the one or more polyhydroxy compounds are present in quantities suchthat the equivalent ratio of the ester groups to the hydroxy groups isfrom 1:1.1 to 1:10, to form an intermediate product Z2 having a numberof hydroxyl groups; (iii) reacting the intermediate product Z2 with (d)one or more polyepoxides having a number of oxirane rings, wherein theintermediate product Z2 and the one or more polyepoxides are present inquantities such that the equivalent ratio of the oxirane rings to thehydroxyl groups is from 1.5:1 to 6:1, to form an intermediate product Z3having a number of oxirane rings; and (iv) reacting the intermediateproduct Z3 with (e) one or more amines selected from the groupconsisting of primary amines and secondary amines having at least oneaminonitrogen atom with one or more reactive hydrogen atoms, wherein theintermediate product Z3 and the one or more amines are present inquantities such that the equivalent ratio of the oxirane rings to thereactive hydrogen atoms is from 1:1.5 to 1:20.
 2. The process accordingto claim 1, wherein the (a) one or more α,β-unsaturated carboxylic acidesters of the general formula (I) comprises a dialkyl maleate.
 3. Theprocess according to claim 2, wherein the dialkyl maleate is selectedfrom the group consisting of dimethyl maleate, diethyl maleate andmixtures thereof.
 4. The process according to claim 1, wherein the (b)one or more aminopolyalkylene oxide compounds comprises amonoaminopolyalkylene oxide compound.
 5. The process according to claim4, wherein the monoaminopolyalkylene oxide compound corresponds to thegeneral formula (II): R⁸—O—R⁹—CH₂CH(R¹⁰)—NH₂  (II) wherein R⁸ representsa monofunctional organic group having from 1 to 12 carbon atoms, R⁹represents a polyoxyalkylene group having from 5 to 200 polyoxyalkyleneunits selected from the group consisting of ethylene oxide, propyleneoxide and statistical or block mixtures thereof, and R¹⁰ representshydrogen or an aliphatic radical having from 1 to 4 carbon atoms.
 6. Theprocess according to claim 4, wherein the monoaminopolyalkylene oxidecompound has an average molecular weight of from 148 to
 5000. 7. Theprocess according to claim 1, wherein the (c) one or more polyhydroxycompounds comprises bisphenol A.
 8. The process according to claim 1,wherein (a) and (b) are present in quantities such that the equivalentratio of the reactive hydrogen atoms in (b) to the α,β C═C double bondsin (a) is from 4:1 to 1:4.
 9. The process according to claim 1, whereinthe intermediate product Z1 and the one or more polyhydroxy compoundsare present in quantities such that the equivalent ratio of the estergroups to the hydroxy groups is from 1:1.4 to 1:3.
 10. The processaccording to claim 1, wherein the intermediate product Z2 and the one ormore polyepoxides are present in quantities such that the equivalentratio of the oxirane rings to the hydroxyl groups is from 2.5:1 to3.5:1.
 11. A hardener for epoxy resins, said hardener produced by theprocess according to claim
 1. 12. A hardener for epoxy resins, saidhardener produced by the process according to claim
 2. 13. A hardenerfor epoxy resins, said hardener produced by the process according toclaim
 4. 14. A hardener for epoxy resins, said hardener produced by theprocess according to claim
 7. 15. An aqueous dispersion comprising ahardener according to claim
 11. 16. The aqueous dispersion according toclaim 15, wherein the hardener comprises dispersed particles having amean particle size of 500 nm or less.